When Elon Musk first started talking about launching a brain-computer interface company, he made a number of comments that set expectations for what that idea might entail. The company, he said, was motivated by his concerns about AI ending up hostile to humans: providing humans with an interface directly into the AI's home turf might prevent hostilities from developing. Musk also suggested that he hoped to avoid any electrodes implanted in the brain, since that might pose a barrier to adoption.

At his recent public launch of the company (since named Neuralink), worries about hostile AIs did get a mention—but only in passing. Instead, we got a detailed technical description of the hardware behind Neuralink's brain-computer interface, which would rely on surgery and implanted hardware. In the process, Neuralink went from something in the realm of science fiction to a company that would be pushing for an aggressive evolution of existing neural-implant hardware.

Those changes in tone and topic are a sign that Musk has been listening to the people he hired to build Neuralink. So, how precisely is Neuralink pushing the envelope on what we can already do in this space? And does it still veer a bit closer to science fiction in some aspects?

The big picture

Before taking a look at the individual components that Neuralink announced recently, let's start with an overview of what the company hopes to accomplish technology-wise. The plan is to access the brain via a hole less than eight millimeters across. This small hole would allow Neuralink to implant an even smaller (4mm x 4mm) chip and its associated wiring into the brain. The chip will get power from, and communicate with, some wireless hardware located behind the ear, much like current cochlear implants.

Inside the brain, the chip will be connected to a series of small threads that carry electrodes to the relevant area, where they can listen in on the electrical activity of neurons. These threads will be put in place using a surgical robot, which allows the surgeon to insert them in a manner that avoids damaging blood vessels.

The chip will take the raw readings of neural activity and process them to a very compact form that preserves key information, which will be easier for their wireless hardware to transmit back across the skull. Electrical impulses can also be sent to the neurons via the same electrodes, stimulating brain activity. Musk thinks that it would be safe to insert as many as 10 of these chips into a single brain, though Neuralink will obviously start testing with far fewer.

All of that is an evolution of some of the existing work on brain-computer interfaces. But the details behind some of these features provides a better sense of how Neuralink is pushing the field forward.

Would you let this robot stick electrodes in your brain?

John Timmer

A look at the robot from Neuralink's presentation (it could pass as an optometrist tool at a glance, no?).

The robot

The Neuralink introduction included a video of the brain during surgery, revealing how the wrinkly organ constantly shifts with breathing and blood flow. This makes implanting electrodes a challenge, especially since much of the brain is laced with blood vessels that the electrodes could easily puncture. Plus, due to their incredibly small size, the electrodes themselves are susceptible to damage.

The robot keeps a surgeon in charge, but it turns the process of electrode implantation into something closer to a video game. Using a microscope integrated into the robot, a surgeon is given a static view of the underlying brain, thanks to software that compensates for the pulsing and shifting. With the static view, implanting the electrodes becomes something like a point-and-click activity: the surgeon selects a location, and the robot inserts the electrode there while compensating for any ensuing movement of the underlying tissue. Although video showed its insertion method as looking like a violent stab, the hardware protects the electrodes from damage at this point.

This method certainly has the potential to make electrode implantation safer, in part by minimizing the risk of blood-vessel damage. But let me be clear: while the electrodes are small enough that they're not dramatically larger than the neurons they interact with, there's still the potential for damage to those neurons or their support cells during the electrode insertion, as well as some disruption of the connections among neurons. That potential may be lowered by the robot, but it's not going away.

One other issue that the robot doesn't obviously solve is that several of the images displayed during the Neuralink introduction showed the chips being located somewhere other than where the electrodes were targeted. There's certainly enough play in the wiring of the electrodes to allow a bit of distance between the two, but it's hard to understand how this can be managed with a single, small surgical incision.

The electrodes

In existing systems, the electrodes are their own distinct hardware component, but Neuralink is seeking to change this. The company hopes to do so by producing the metal portion of the electrodes as it's building layers of metal into the chips used for processing the electrode data. This provides some real advantages, as the process technology used there is already operating at the sort of fine scales that make structure of the electrodes easy.

This setup would also do away with any bulky connector hardware currently needed to link electrodes with the rest of the system—they're already part of it. Presumably, Neuralink will manufacture chips with electrodes of different lengths to allow for flexibility in the implantation process.

In use, multiple electrodes will be combined into a single "thread," with polymer layers providing insulation to avoid cross-talk. Additional polymer layers will protect the thread from the environment of the brain, which Vanessa Tolosa of Neuralink described as "harsh." The electrode and polymer materials were both chosen to limit inflammatory and other immune responses.

Overall, this part of Neuralink's approach seemed solid, although a full evaluation will have to wait for longer-term studies of a thread's safety and useful lifetime inside an actual brain. Scar development was a real problem with early electrodes made by others, but further development has limited this problem. Presumably, Neuralink has already learned from others here.